Field of the Invention
The present invention relates to an image forming apparatus, and a calibration technique for maintaining the quality of an image formed by the image forming apparatus.
Description of the Related Art
The image quality of an image forming apparatus varies depending on the environment in which the image forming apparatus is used, or the status of use of the image forming apparatus. This requires calibration to update image forming conditions (such as a correction condition and a process condition) depending on the environment or the status of use. Dedicated paper for calibration, which is designated by the manufacturing company of the image forming apparatus, needs to be used in calibration. If the dedicated paper for calibration has run out, it is impossible to obtain an accurate calibration result. U.S. Patent Application Publication No. 2010/0315685 describes an image forming apparatus that can, even when any recording medium different from dedicated paper for calibration is used, obtain the same calibration result as when the dedicated paper is used.
An accumulation of various errors in calibration has been found to likely cause a decrease in density reproducibility in a high density region. In view of this, the present invention improves the calibration accuracy in the high density region.